Method for protecting the diaphragm and extending the life of SiC and/or Si MEMS microvalves

Abstract

A microvalve and a method of forming a diaphragm stop for a microvalve. The microvalve includes a first layer and a diaphragm member to control the flow of fluid through the microvalve. The method comprises the step of forming a contoured shaped recess extending inward from a surface of the layer by using a laser to remove material in a series of areas, at successively greater depths extending inward from said surface. Preferably, the recess has a dome shape, and may be formed by a direct-write laser operated via a computer aided drawing program running on a computer. For example, CAD artwork files, comprising a set of concentric polygons approximating circles, may be generated to create the dome structure. The laser ablation depth can be controlled by modifying the offset step distance of the polygons and equating certain line widths to an equivalent laser tool definition. Preferably, the laser tool definition is combined with the CAD artwork, which defines a laser path such that the resulting geometry has no sharp edges that could cause the diaphragm of the valve to tear or rupture.

What is claimed is:  
     
       1. A method of forming a diaphragm stop for a microvalve, the microvalve including a first layer and a diaphragm member to control the flow of fluid through the microvalve, the method comprising the step of: 
       forming a contoured shaped recess extending inward from a surface of the layer, including the step of  
       using a laser to remove material in a series of areas, at successively greater depths extending inward from said surface.  
     
     
       2. A method according to  claim 1 , wherein the step of using a laser includes the step of using the laser to remove mateial in a series of generally concentric areas, at successively greater depths extending inward from said surfaces. 
     
     
       3. A method according to  claim 1 , wherein the forming step includes the step of forming a smooth contoured shaped recess extending inward from the surface of the layer. 
     
     
       4. A method according to  claim 2 , wherein adjacent concentric areas are spaced apart between 1 and 10 um. 
     
     
       5. A method according to  claim 1 , wherein each of said areas is polygon shaped. 
     
     
       6. A method according to  claim 5 , wherein each of said areas is a polygon having at least thirty sides. 
     
     
       7. A method according to  claim 1 , wherein each of said areas is circular. 
     
     
       8. A method according to  claim 2 , wherein said series of concentric areas are uniformly spaced apart. 
     
     
       9. A method according to  claim 1 , wherein the step of using a laser includes the steps of: 
       using a computer to control movement of the laser; and  
       programming the computer to control the laser to ablate a series of concentric, polygon shaped areas from the layer, said series extending inward from the surface of the layer.  
     
     
       10. A method according to  claim 1 , wherein in the microvalve, the diaphragm member includes a central portion that moves between open and closed positions, and in the open position, the central portion of the diaphragm has a given shape, and the step of forming the recess includes the step of forming the recess with a shape that substantially matches said given shape. 
     
     
       11. A method according to  claim 1 , wherein the diaphragm member has a thickness of substantially 0.0125 mm and, the recess has a diameter of substantially 1.270 mm and a depth of substantially 0.025 mm.